1. Field of the Invention
The present invention relates to an image forming system, intermediate transfer medium and method that forms an image on an image recording member by way of the intermediate transfer medium, and particularly to an image forming system, intermediate transfer medium and method that temporarily attaches color particles of an image forming substance on the intermediate image transfer device before transferring the image to the recording member.
2. Description of the Related Art
In conventional image-forming processes, devices such as laser printers, electrophotographic copy machines and the like employ an electrophotographic process to reproduce an image. Ink jet printing processes and a mimeograph processes are also known as image forming processes. However, such conventional processes do not operate without flaw. In the electrophotographic process, photoconductive characteristics of the photoconductive device are time varying and degrade with time and use. This process also produces harmful ozone gas as a result of corona discharge from high voltage sections of the apparatus. As for ink jet printing, such devices are slow. As for mimeograph printing, resulting image resolution is low, despite the fact that a sophisticated process is employed to make a master edition plate, from which the copies are made.
Another type of image forming process is disclosed in Japanese Laid Open patent application No. 64-69,357, as shown in FIG. 1. Referring to FIG. 1, a conceptional image forming mechanism is shown, where a layer of toner particles 1001 is conveyed on a translucent resin film 1000 toward a printing paper 1002. The resin film 1000 is translucent so as to allow a laser beam 1004 to pass through the film and melt the toner particles 1001.
In this image forming mechanism, the toner particles 1001 are stuck to one side of the resin film 1000 such that the toner particles 1001 are carried toward the printing paper 1002 at the location where the laser beam 1004 is incident with the resin film 1000. The laser beam 1004 is ON-OFF modulated with image signals, under control of an image processor, such that when the laser beam 1004 is turned on, the light irradiates the back surface of the resin film, opposite to the side on which the toner particles 1001 are lightly held in place. Energy from the laser beam 1004 passes through the resin film 1000 and is absorbed in a top portion of respective toner particles. This light energy melts the top portion of illuminated toner particles and eventually melts the bottom portion of the illuminated toner particles, if the laser light is of sufficient intensity and is applied for a sufficient period of time. Accordingly, the portion of the particle that first receives the laser light is the first to melt, and the portion contacting the printing paper 1002 melts at a later time. When the portion of the toner particle contacting the printing paper 1002 melts, the molten toner particle adheres to the printing paper 1002 so as to form the image on the printing paper 1002.
Referring to FIG. 2, another image forming process is disclosed in Japanese Laid Open patent application 07-314,746. In this process, the printing paper 1002 is brought in contact with a roller 2002 that has the toner particles 1001 disposed on the surface of the roller 2002. A thermal head 2004 is located on the opposite side of the printing paper 1002, with respect to the roller 2002. In response to receiving image signals, the thermal head provides heat in bursts so as to heat the printing paper and fuse the image into the printing paper for particular picture elements.
The present inventor identified that the above-described devices are suboptimal in several aspects. In the device shown in FIG. 1, heat from the light beam 1004 must be of sufficiently high power to melt the entirety of the toner particles 1001 corresponding to the image data. Thus, the light energy must be sufficient to pass through the resin sheet 1001 and to the portion of the toner particles 1001 adjacent to the printing paper 1002 so as to fuse the toner image to the printing paper. Moreover, because the toner adhesion surface between the printing paper 1002 and the toner particles 1001 is located on the opposite side of the incidence direction of the light beam, the light beam is not capable of directly heating the toner adhesion surface between the printing paper and the toner layer. Consequently, the heat intensity of the light beam 1004 and the duration of application of the light beam imparts more energy than necessary into the toner particles 1001 and thus, increases system power draw demands, and raises internal heat dissipation demands. A related problem is one of image resolution. By having to melt nearly the entire toner particle before the toner particle will adhere to the printing paper 1002, heat imparted into a target toner particle may cause adjacent toner particles to melt and inadvertently adhere to the printing paper 1002.
With respect to the device and method described in FIG. 2, the thermal head 2004 heats the printing paper 1002 on the side of the paper opposite the toner adhesion surface. Accordingly, it is difficult to regulate the amount of heat needed to propagate through the printing paper 1002 so as to assuredly make the toner particles 1001 adhere to the paper 1002. This uncertainty is particularly pronounced if the thickness of the paper varies, or the attraction force of the toner particles 1001 to the roller 2002 (often a magnetic force) is not finely controlled.
Accordingly, an object of the present invention is to address and overcome the above-mentioned and other limitations of conventional devices. This and other objects are accomplished by the present invention, a brief non-exhaustive summary of selected features of which is provided in the present section.
According to the present invention, an image forming system employs an intermediate transfer device, such as a belt, to host image forming substance particles that are temporarily go attached thereto and arranged in a shape that corresponds with an image to be printed on a sheet. Moreover, the image forming substance particles are provisionally transferred and temporarily attached on the intermediate image transfer device by supplying heat, corresponding to image signals and partially melting the portion of the image forming substance particles (or belt) that will be attached to the intermediate transfer device (or particle). The intermediate transfer device then conveys the image forming substance particles, which are temporarily attached thereto, to an image transfer mechanism that transfers the image forming substance particles from the intermediate transfer device to the sheet where the image is then affixed thereto.